The theory stems from Penrose’s notion that there is an element of non-computability within brain processes. Most physical processes are deterministic, and Penrose has singled out wave function collapse as the only non-deterministic aspect of nature. This is conventionally understood as being a random process, not apparently of much value to human cognition. Penrose, however, proposes an additional form of wave function collapse, objective reduction (OR), which is suggested to occur when the quantum wave is not collapsed by interaction with the environment or by a measurement.

The quantum wave represents superpositions of the different possible states of a quantum particle. Each superposition of a particle is viewed as having its own spacetime geometry, with each superposition possessing a slightly different geometry, and the separation between these comprising a form of blister or bubble in spacetime. When this separation reaches the Planck length, it reaches a critical threshold of instability, and rapidly collapses to a single state of the particle. It is suggested that in this case the choice of state is not random, but based on a non-computable process that is neither deterministic nor random. This process is suggested to be based on the configuration of networks that make up and drive the dynamic development of spacetime. Hameroff suggests that qualia, raw subjective experiences such as the redness of red, are encoded in the spin networks that may constitute space time. The sensation of having free will is also suggested to be a function of this non-computable process.

Penrose sometimes describes the spacetime where mathematical understanding and other aspects of the mind are suggested to be encoded as the Platonic realm. This refers back to Plato’s idea that the physical world reflected ideals or ideas embodied in a separate realm. This has tended to be a target of ridicule for modern critics, such as Patricia Churchland. Spiers and Thomas advance the somewhat odd objection to Orch OR that if human ideas were derived from a Platonic realm or Platonic logic all human opinions would be the same. Hameroff’s counter view is that spacetime geometry is dynamic and evolving, and also that only part of the influence on individual minds derives from spacetime, with the mind also be governed by conventional inputs from inheritance and environment.

Spier and Thomas appear to have something of a mantra to the effect that protein molecules are the basic computational elements in neurons. Hameroff in fact agrees with this, but suggests that the conformation is governed by quantum van der Waals forces, occurring mainly in hydrophobic pockets within the proteins. Anaesthetic molecules which oblate consciousness are thought to bind in such pockets.
Spier and Thomas somewhat weaken their case by trundling out the old argument that microtubules are too unstable to form a basis for consciousness. This at least is easily answered by the fact that brain microtubules are much more stable and form part of a dense cytoskeletal structure.

The argument moves on to the issue of single celled creatures, such as paramecium. Hameroff has suggested that these can navigate and respond to their environment without a nervous system as a result of microtubule processing. Spier and Thomas counter with the example of bacteria, which can also navigate themselves but lack microtubules. Hameroff quotes a study (Lowe & Amos, 1.) indicating that bacteria have protein based circuits resembling tubulin, the protein from which microtubules are built.